Resonances in the rotational constants of Cs₂ levels analysed by an improved-B_v-formula associated to a 2-channel model

¹ Laboratoire de Recherche Energie et Matière pour les Développements des Sciences Nucléaires (LR16CNSTN02) & Direction de la Recherche sur l'Energie et la Matière, National Centre for Nuclear Science and Technology Sidi Thabet Technopark 2020, Ariana, Tunisia
² Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS-Cachan, Université Paris-Saclay 91405, Orsay, France

^(a) haikel.jelassi@cnstn.rnrt.tn
haikel.jelassi@gmail.com
^(b) laurence.pruvost@u-psud.fr

Received: 27 May 2016
Accepted: 27 August 2016

Abstract

Spin-orbit coupling in long-range molecular levels of Cs₂ assigned to resonances in the rotational constant spectrum (Lignier L. et al., Phys. Chem. Chem. Phys., 13 (2011) 18910; Pichler M. et al., J. Chem. Phys., 121 (2004) 1796) has been analyzed with a model which associates an improved-B_v-formula (established here) and a 2-channel model. The approach explains the Lorentzian shape of the observed resonances superimposing a non-horizontal background and the fit of the B_v-spectrum allows us to deduce the spin-orbit coupling parameters. We compare this approach with an analysis of the binding energies using the vibrational quantum defect (VQD). The good agreement between the methods lets one conclude that the improved-B_v-formula associated with a 2-channel model provides a pertinent approach for analyzing coupled molecular series.